Polyurethane transmission belts are used in general industrial machinery, OA equipment, etc. Such polyurethane transmission belts are formed by a belt-molding material that contains prepolymer synthesized from trirange isocyanate or other polyisocyanate and polytetramethylene ether glycol or other polyol, 1,1′-methylene bis (o-chloroaniline) or other curing agent, plasticizer, and other additives. This belt-molding material is poured into belt-molding dies and thermally cured into a cylinder shape, after which the cylinder is sliced to the necessary width to manufacture a polyurethane transmission belt.
Polyurethane transmission belts offering improved durability are desired, because they are used for a long period of time under tension.
Patent Literature 1 proposes a polyurethane transmission belt whose durability is improved by adding a lubricant constituted by a grease of 50 to 80° C. in melting point whose primary component is triglyceride. Because it contains a grease of 50 to 80° C. in melting point, this polyurethane transmission belt offers improved durability so long as it is used in a temperature range of room temperature to around 50° C.; however, this belt presents a problem in that the grease seeps onto the belt surface to produce bloom at low temperatures below room temperature, making the belt not durable enough in a low-temperature environment.